Extensible polypropylene-based nonwovens

ABSTRACT

Disclosed herein is a nonwoven fabric comprising within the range of from 50 to 99 wt %, by weight of the composition, of a reactor grade propylene-α-olefin copolymer possessing within the range of from 5 to 35 wt %, by weight of the copolymer, of units derived from one or more of ethylene and/or C 4  to C 12  α-olefins; a melt flow rate (230° C./2.16 kg) within the range of from 500 to 7500 g/10 min; and a weight average molecular weight of less than 200,000; and a second polypropylene having a melting point, T m , of greater than 110° C. and a melt flow rate (230° C./2.16 kg) within the range of from 20 to 7500 g/10 min; wherein the fabric has a CD Elongation value of greater than 50% (measuring the fabric of 35 g/m 2  basis weight). The fabric described herein can be used in structures comprising one or more layers of the fabric described herein, and can include any number of other fabric layers made from other materials.

PRIORITY CLAIM

This application is a continuation-in-part of U.S. Ser. No. 10/969,489,filed Oct. 20, 2004 now abandoned, which is a continuation-in-part ofU.S. Ser. No. 10/716,306, filed Nov. 18, 2003 now abandoned.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application for patent is filed concurrently with, and isrelated to, U.S. Ser. No. 12/185,491 filed on Aug. 4, 2008, incorporatedherein by reference.

FIELD OF THE INVENTION

The present invention relates in general to soft, extensible fabricscomprising propylene-based polymers, and more particularly relates topropylene-based nonwoven fabrics comprising a propylene-α-olefincopolymer that is a low molecular weight reactor grade polymer suitablefor melt blowing.

BACKGROUND

Soft and elastic nonwoven fabrics of polypropylene and its copolymerswith α-olefins such as ethylene which lead to substantially softer andmore extensible constructions are desirable, yet often difficult toobtain with the right balance of properties. U.S. Pat. Nos. 3,853,969and 3,378,606, suggest the formation of in situ blends of isotacticpolypropylene and “stereo block” copolymers of propylene and anotherolefin of 2 to 12 carbon atoms, including ethylene and hexene to yieldblends which may be fabricated to obtain soft and elastic nonwovenfabrics. Similar results are discussed in U.S. Pat. Nos. 3,262,992,3,882,197, and 3,888,949, which suggests the synthesis of blendcompositions containing isotactic polypropylene and copolymers ofpropylene and an α-olefin, containing between 6-20 carbon atoms, whichare softer and have improved elongation and tensile strength over eitherthe copolymer or isotactic polypropylene. Copolymers of propylene andα-olefin are described wherein the α-olefin is hexene, octene ordodecene.

Examples of propylene homopolymers containing different levels ofisotacticity in different portions of the molecule are described in U.S.Pat. No. 5,594,080, in the article in 117 JOURNAL AMERICAN CHEMICALSOCIETY 11586 (1995), in the article in 119 JOURNAL AMERICAN CHEMICALSOCIETY 3635 (1997), in the journal article in 113 JOURNAL OF THEAMERICAN CHEMICAL SOCIETY 8569-8570 (1991), and in the journal articlein 28 JOURNAL MACROMOLECULES 3771-3778 (1995). U.S. Pat. Nos. 5,723,217;5,726,103; 5,736,465; 5,763,080; and 6,010,588 suggest severalmetallocene catalyzed processes to make polypropylene suitable forfibers and fabrics. U.S. Pat. No. 5,891,814 discloses a dualmetallocene-generated propylene polymer used to make spunbond fibers. WO99/19547 discloses a method for producing spunbonded fibers and fabricderived from a blend of a propylene homopolymer and a copolymer ofpolypropylene. U.S. Pat. No. 6,342,565, U.S. 2005/0130544 A1 and U.S.2006/0172647 discloses a fiber or nonwoven fabric.

These past disclosures have generally taught that fabricating a nonwovenfabric from a fiber to form a soft or extensible article generallyrequires the use of a semicrystalline polymer. These semicrystallinepolymers are most conveniently made at a high molecular weight (aboveabout 250,000 daltons weight average molecular weight), yet the processof manufacture of the fiber and the fabric, especially meltblown fibersand fabrics, requires a polymer of a lower molecular weight (less thanabout 250,000 daltons weight average molecular weight). The lowermolecular weight is typically achieved by free radical assisted thermalprocesses (“controlled rheology”). While isotactic polypropylene hasbeen produced at a low enough molecular weight for it to be used withoutpost-reactor degradation, less crystalline polymers containing limitedamounts of crystallinity have not been made useful for the fabricationof a fiber and a nonwoven fabric.

SUMMARY

Disclosed herein in one embodiment is a nonwoven fabric comprisingwithin the range of from 50 to 99 wt %, by weight of the fabric, of areactor grade propylene-α-olefin copolymer possessing within the rangeof from 5 to 35 wt %, by weight of the copolymer, of units derived fromone or more of ethylene and/or C₄ to C₁₂ α-olefins; a melt flow rate(230° C./2.16 kg) within the range of from 500 to 7500 g/10 min; and aweight average molecular weight of less than 200,000; and a secondpolypropylene having a melting point, T_(m), of greater than 110° C. anda melt flow rate (230° C./2.16 kg) within the range of from 20 to 7500g/10 min; wherein the fabric has a CD Elongation value of greater than50% (measuring the fabric of 35 g/m² basis weight).

The fabric described herein can be used in structures comprising one ormore layers of the fabric described herein, and can include any numberof other fabric layers made from other materials.

The various descriptive elements and numerical ranges disclosed hereincan be combined with other descriptive elements and numerical ranges todescribe preferred embodiments of the invention(s); further, any uppernumerical limit of an element can be combined with any lower numericallimit of the same element to describe preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graphical representation of the correlation betweenmolecular weight (Mn and Mw) and MFR (230° C., 2.16 kg) for reactorgrade propylene-α-olefins as described herein and commercial grades ofVistamaxx™ polymers of relatively low MFR.

DETAILED DESCRIPTION

Described herein are meltblown fibers and the derived nonwoven fabrics(“fabrics”) comprising reactor grade propylene-α-olefin copolymer(s)wherein the fabric has a CD Elongation value of greater than 50%(measuring the fabric of 35 g/m² basis weight). The fabrics can be madeby any conventional means known in the art, but are preferably producedby a meltblown process. The meltblown process used is not particularlylimited, as long as the desirable elasticity of the fabric, as expressedat least by the CD Elongation, is maintained. Further, the softness andelasticity of the fabric can be adjusted by any combination (within thelimits of the description herein) of the amounts and/or identity of thecomponents used to make the fabric. In certain embodiments, the fabricscomprise—consist essentially of in a particular embodiment—a reactorgrade propylene-α-olefin copolymer and a “second” polypropylene, both ofwhich are described in more detail below. By “consists essentially of,”what is meant is that there are no other additive(s) in the fabrics thatare present to greater than a total of 5 wt %, based on the weight ofthe fabric.

As used herein, “fabric” is a structure (preferably flat) that has athickness such that it impedes, but does not stop, the passage of airand/or water, the fabric made from fibers that are bound togetherthrough chemical bonding, melt adhesion or weaving such that they formthe fabric.

Reactor Grade Propylene-α-Olefin Copolymer (“RGP”)

The “reactor grade propylene-α-olefin copolymer” described herein is areactor grade copolymer, meaning that it has not been subjected to anypost polymerization chemical process such as chain scissioning,grafting, etc., that will alter its weight average molecular weight byany more than 2%. The “reactor grade propylene-α-olefin copolymers”(“RGP”) used in the fibers and fabrics described herein arecrystallizable copolymers of propylene and at least one of ethyleneand/or a C₄ or higher α-olefin, ethylene in a particular embodiment. A“crystallizable” polymer—distinct from a “crystalline” polymer—is apolymer where the measured crystallinity of the polymer as measured bythe heat of fusion (by DSC, as described in the procedure below) isaugmented at least by a factor of 1.5, or 2, or 3 by either waiting fora period of 120 hours at room temperature, by singly or repeatedlymechanical distending the sample, or by contact with another crystallinepolymer such as isotactic polypropylene. Certain aspects of the fabricsdescribed herein relate to the inclusion of a low molecular weight(weight average molecular weight of less than 200,000 daltons) reactorgrade propylene α-olefin copolymer which has some or all of the belowfeatures.

In certain embodiments, the reactor grade propylene-α-olefin copolymeris prepared by reacting propylene, an ethylene and/or another α-olefin(preferably ethylene) and a single site catalyst composition, preferablya metallocene catalyst composition. Preferably, chain scissioningbyproducts, as are known in the art, are substantially absent from thereactor grade propylene-α-olefin copolymer, meaning that if suchbyproducts are present, they are only present to less than 1 wt %, byweight of the copolymer.

The “RGPs” described herein are copolymers of propylene-derived unitsand one or more units derived from ethylene and/or a C₄-C₁₂ α-olefin.The overall comonomer content of the copolymer is within the range offrom 5 to 35 wt % by weight of the RGP. In general, the comonomercontent and the conditions for producing the RGP are adjusted so thatthe RGP has a molecular weight distribution (Mw/Mn) within the range offrom 1.5 to 20, a heat of fusion (ΔH_(f)) of from less than or equal to75 J/g, and a peak melting temperature (T_(m)) within the range of from0° C. to 100° C. In some embodiments, where more than one comonomer ispresent, the amount of a particular comonomer may be less than 5 wt %,but the combined comonomer content is preferably greater than 5 wt %.The RGPs may be described by any number of different parameters, andthose parameters may comprise a numerical range made up of any desirableupper limit with any desirable lower limit as described herein for theRGPs.

In certain embodiments, when there is more than one α-olefin-derivedunit in the copolymer, the total weight percent of the ethylene and/orC₄-C₁₀ α-olefin-derived units (or “α-olefin”) is within the range offrom 5 to 35 wt %, and from 7 to 32 wt % in another embodiment, and from8 to 25 wt % in yet another embodiment, and from 8 to 20 wt % in yetanother embodiment, and from 8 to 18 wt % in a particular embodiment.Non-limiting examples of copolymers, or “terpolymers,” having more thanone α-olefin include propylene-ethylene-octene,propylene-ethylene-hexene and propylene-ethylene-butene polymers. In aparticular embodiment, the RGP comprises propylene-derived units andcomonomer units selected from ethylene, 1-butene, 1-hexene and 1-octene,and preferably ethylene. Thus the RGP is preferably a propylene-ethylenecopolymer.

In certain embodiments, the RGPs have a triad “mm” tacticity of threepropylene units, as measured by ¹³C NMR, of 75% or greater, 80% orgreater, 82% or greater, 85% or greater, or 90% or greater. In oneembodiment, the triad “mm” tacticity is within the range of from 50 to99%, and from 60 to 99% in another embodiment, and from 75 to 99% in yetanother embodiment, and from 80 to 99% in yet another embodiment; andfrom 60 to 97% in yet another embodiment. Triad tacticity is determinedby calculation of the peak areas PPP(mm), PPP(mr) and PPP(rr) derivedfrom the methyl groups of the second units in the following threepropylene unit chains consisting of head-to-tail bonds. The ¹³C NMRspectrum of the propylene copolymer is measured as described in U.S.Pat. No. 5,504,172. The spectrum relating to the methyl carbon region(19-23 parts per million (ppm)) can be divided into a first region(21.2-21.9 ppm), a second region (20.3-21.0 ppm) and a third region(19.5-20.3 ppm). Each peak in the spectrum was assigned with referenceto 30 POLYMER 1350 (1989). In the first region, the methyl group of thesecond unit in the three propylene unit chain represented by PPP (mm)resonates. In the second region, the methyl group of the second unit inthe three propylene unit chain represented by PPP(mr) resonates, and themethyl group (PPE-methyl group) of a propylene unit whose adjacent unitsare a propylene unit and an ethylene unit resonates (in the vicinity of20.7 ppm). In the third region, the methyl group of the second unit inthe three propylene unit chain represented by PPP(rr) resonates, and themethyl group (EPE-methyl group) of a propylene unit whose adjacent unitsare ethylene units resonates (in the vicinity of 19.8 ppm). Thecalculation of the triad tacticity is outlined in the techniques shownin U.S. Pat. No. 5,504,172. Subtraction of the peak areas for the errorin propylene insertions (both 2,1 and 1,3) from peak areas from thetotal peak areas of the second region and the third region, the peakareas based on the 3 propylene units-chains (PPP(mr) and PPP(rr))consisting of head-to-tail bonds can be obtained. Thus, the peak areasof PPP(mm), PPP(mr) and PPP(rr) can be evaluated, and hence the triadtacticity of the propylene unit chain consisting of head-to-tail bondscan be determined.

An alternate mode of expressing the stereoregularity of the propyleneinsertion is by the tacticity index. The insertion of propylene canoccur by either 2,1 (tail-to-tail) or 1,3 insertions (end-to-end). Suchdetermination is outlined in U.S. Pat. No. 5,504,172. The proportion ofthe 2,1-insertions to all of the propylene insertions in the RGPs wascalculated by the following formula with reference to 30 POLYMER 1350(1989): Proportion of inversely inserted unit based on 2,1-insertion(%)=100×[0.25 I_(αβ)(structure (i))+0.5I_(αβ)(structure(ii))]/[I_(αα)+I_(αβ)(structure (ii))+0.5(I_(αγ)+I_(αβ)(structure(i))+I_(αδ))]. Naming of the peaks in this formula was done inaccordance with a method of Carman, et al. in 44 RUBBER CHEMISTRY ANDTECHNOLOGY 781 (1971), where I_(αδ) denotes a peak area of the αδ⁺secondary carbon peak. It is difficult to separate the peak area ofI_(αβ) (structure (i)) from I_(αβ) (structure (ii)) because ofoverlapping of the peaks. Carbon peaks having the corresponding areascan be substituted therefore.

The measurement of the 1,3 insertion requires the measurement of the βγpeak. Two structures can contribute to the βγ peak: (1) a 1,3-insertionof a propylene monomer; and (2) from a 2,1-insertion of a propylenemonomer followed by two ethylene monomers. This peak is described as the1.3 insertion peak and the procedure described in U.S. Pat. No.5,504,172 is used, which describes this βγ peak as understood torepresent a sequence of four methylene units. The proportion (%) of theamount of these errors was determined by dividing the area of the βγpeak (resonance in the vicinity of 27.4 ppm) by the sum of all themethyl group peaks and ½ of the area of the βγ peak, and thenmultiplying the resulting value by 100. If an α-olefin of three or morecarbon atoms is polymerized using an olefin polymerization catalyst, anumber of inversely inserted monomer units are present in the moleculesof the resultant olefin polymer. In polyolefins prepared bypolymerization of α-olefins of three or more carbon atoms in thepresence of a chiral metallocene catalyst, 2,1-insertion or1,3-insertion takes place in addition to the usual 1,2-insertion, suchthat inversely inserted units such as a 2,1-insertion or a 1,3-insertionare formed in the olefin polymer molecule (see, K. Soga, T. Shiono, S.Takemura and W. Kaminski in 8 MACROMOLECULAR CHEMISTRY RAPIDCOMMUNICATION 305 (1987)). In certain embodiments, the RGPs have aproportion of inversely inserted propylene units, based on the2,1-insertion of a propylene monomer in all propylene insertions asmeasured by ¹³C NMR, is greater than 0.5%, or greater than 0.6%. Incertain embodiments, the RGPs have a proportion of inversely insertedpropylene units, based on the 1,3-insertion of a propylene monomer, asmeasured by ¹³C NMR is greater than 0.05%, or greater than 0.06%, orgreater than 0.07%, or greater than 0.08%, or greater than 0.085%.

In certain embodiments, the RGPs have a heat of fusion (ΔH_(f)),determined according to the Differential Scanning Calorimetry (DSC)procedure described herein, within the range of from 0.5 or 1 or 5 J/gto 30 or 35 or 40 or 50 or 60 or 75 J/g. In certain embodiments, theRGPs have a percent crystallinity within the range of from 0.25 or 0.5or 1 or 2 to 25 or 30 or 40%. The crystallinity is calculated based onthe assumption that the thermal energy for the highest order ofpolypropylene is estimated at 189 J/g (i.e., 100% crystallinity is equalto ΔH_(f) of 189 J/g). In yet other embodiments, the RGPs have acrystallization temperature (T_(c)) within the range of from 0 or 5 to15 or 20 or 30 or 40° C.

In certain embodiments, the RGPs have a single peak melting transitionas determined by DSC; in certain embodiments the RGP has a primary peakmelting transition at from less than 90° C., with a broad end-of-melttransition at greater than about 110° C. The peak “melting point”(T_(m)) is defined as the temperature of the greatest heat absorptionwithin the range of melting of the sample. However, the RGP may showsecondary melting peaks adjacent to the principal peak, and or theend-of-melt transition, but for purposes herein, such secondary meltingpeaks are considered together as a single melting point, with thehighest of these peaks being considered the T_(m) of the RGP. In certainembodiments, the RGPs have a peak melting temperature (T_(m)) within therange of from 0 or 5 or 10 or 20 or 25° C. to 65 or 70 or 80 or 100° C.,and a T_(m) of less than 80 or 100° C. in other embodiments.

In certain embodiments, the RGPs have a density within the range of from0.850 to 0.920 g/cm³, and from 0.870 to 0.900 g/cm³ in anotherembodiment, and from 0.880 to 0.890 g/cm³ in yet another embodiment, thevalues measured at room temperature per the ASTM D-1505 test method.

In certain embodiments, the RGPs have a melt flow rate (“MFR” ASTMD1238, 2.16 kg, 230° C. as used throughout) of greater than 500 or 800or 1000 or 1200 g/10 min; and the MFR for the RGPs is within the rangeof from 500 or 800 or 1000 g/10 min to 3000 or 3500 or 4000 or 5000 or6000 g/10 min in other embodiments.

In certain embodiments, the RGPs have a weight average molecular weight(Mw) value within the range of from 5,000 or 10,000 or 20,000 or 30,000to 70,000 or 80,000 or 100,000 or 150,000 or 200,000 daltons; and lessthan 200,000 or 150,000 or 100,000 or 80,000 daltons in otherembodiments. In certain embodiments, the RGPs have a number averagemolecular weight (Mn) value within the range of from 10,000 or 15,000 to40,000 or 50,000 or 80,000 or 100,000 daltons; and less than 80,000 or50,000 in other embodiments. In certain embodiments, the molecularweight distribution (MWD) of the RGPs is within the range of from 1.5 or1.8 or 2 to 3.5 or 4 or 5 or 10 or 20. Techniques for determining themolecular weight (Mn, Mz and Mw) and MWD are as in Verstate et al. in 21MACROMOLECULES 3360 (1988) and as described below. Conditions describedherein govern over published test conditions.

Although the “reactor grade propylene-α-olefin” component of the fibersand fabrics described herein have been discussed as a single polymer,the term “RGP” includes blends of two or more RGPs, preferably, havingthe properties described herein, are also contemplated.

The RGPs can be prepared in a single stage, steady state polymerizationprocess conducted in a well-mixed continuous feed polymerizationreactor. The polymerization can be conducted in solution, although otherpolymerization procedures such as gas phase or slurry polymerization,which fulfill the requirements of single stage polymerization andcontinuous feed reactors, may also be used. The RGPs can be prepared bypolymerizing a mixture of propylene and one or more other α-olefins inthe presence of a chiral catalyst (preferably a chiral metallocene),wherein a copolymer is obtained comprising up to 35% by weight ethyleneand/or higher α-olefins and preferably up to 20% by weight ethyleneand/or higher α-olefins containing isotactically crystallizablepropylene sequences, in a single stage or multiple stage reactor.Generally, without limiting in any way the scope described herein, oneprocess for the production of the RGP is as follows: (1) liquidpropylene is introduced in a stirred-tank reactor which is completely orpartly full of liquid comprising the solvent, the propylene copolymersas well as dissolved, unreacted monomer(s) and catalyst components, (2)the catalyst system is introduced via nozzles in either the vapor orliquid phase, (3) feed ethylene gas and any higher α-olefins areintroduced either into the vapor phase of the reactor into the liquidphase as is well known in the art, (4) the reactor contains a liquidphase composed substantially of propylene, together with dissolvedethylene and/or higher α olefin, and a vapor phase containing vapors ofall monomers, (5) the reactor temperature and pressure may be controlledvia reflux of vaporizing propylene (autorefrigeration), as well as bycooling coils, jackets, etc., (6) the polymerization rate is controlledby the concentration of catalyst, temperature, and (7) the ethyleneand/or higher α-olefin content of the polymer product is determined bythe ratio of ethylene and/or higher α-olefin to propylene in thereactor, which is controlled by manipulating the relative feed rates ofthese components to the reactor; and the molecular weight (and melt flowrate) is controlled in party by addition of chain terminating agentssuch as hydrogen and/or control of the temperature, where a highertemperature tends to decrease the molecular weight.

A typical polymerization process consists of a polymerization in thepresence of a catalyst comprising a chiral bis(cyclopentadienyl) Group 4metal (preferably hafnium) compound, a bridged Group 4 metallocene in aparticular embodiment, and either: (1) a non-coordinating compatibleanion activator or (2) an alumoxane activator. An exemplary catalystsystem is described in U.S. Pat. No. 5,198,401, incorporated herein byreference. The alumoxane activator is preferably utilized in an amountto provide a molar aluminum-to-metallocene ratio of from 1:1 to 20,000:1or more. The non-coordinating compatible anion activator is preferablyutilized in an amount to provide a molar ratio of biscyclopentadienylmetal compound to non-coordinating anion of 10:1 to 2:3. The abovepolymerization reaction is conducted by reacting such monomers in thepresence of such catalyst system at a temperature within the range offrom −50 or 0 or 10 or 50 or 80 or 90° C. to 120 or 150 or 200° C.; andin certain embodiments for a time of from about 1 second to about 10hours to produce a copolymer or terpolymer having the characteristicsdescribed herein.

Descriptions of useful ionic catalysts for polymerization of olefinsusing metallocene cations activated by non-coordinating anions appear inU.S. Pat. Nos. 5,198,401 and 5,278,119, and WO 92/00333. Thesereferences suggest a method of preparation wherein metallocenes (bis Cpand mono Cp) are protonated by anionic precursors such that analkyl/hydride group is abstracted from a transition metal to make itboth cationic and charge-balanced by the non-coordinating anion. The useof ionizing ionic compounds not containing an active proton but capableof producing both the active metallocene cation and a non-coordinatinganion are also useful herein. Reactive cations other than Bronsted acidscapable of ionizing the metallocene compounds include ferrocenium,triphenylcarbonium, and triethylsilylium cations. Any metal or metalloidcapable of forming a coordination complex which is resistant todegradation by water (or other Bronsted or Lewis acids) may be used orcontained in the anion of the second activator compound. Suitable metalsinclude, but are not limited to, aluminum, gold, platinum and the like.Suitable metalloids include, but are not limited to, boron, phosphorus,silicon and the like.

An additional method of making the ionic catalysts uses ionizing anionicprecursors which are initially neutral Lewis acids but form the cationand anion upon ionizing reaction with the metallocene compounds. Forexample tris(pentafluorophenyl) boron acts to abstract an alkyl, hydrideor silyl ligand to yield a metallocene cation and stabilizingnon-coordinating anion. Ionic catalysts useful herein for additionpolymerization can also be prepared by oxidation of the metal centers oftransition metal compounds by anionic precursors containing metallicoxidizing groups along with the anion groups.

In certain embodiments, a process for preparing blend compositions (thatinclude at least the RGP and SPP) comprises the steps of: (a)polymerizing a mixture of ethylene and propylene in the presence of achiral metallocene catalyst to obtain a copolymer comprising from about65% to about 95% propylene by weight of the copolymer having an MFRgreater than 500 dg/min; (b) providing a polypropylene that is asubstantially isotactic propylene copolymer comprising from, forexample, from 91% to 99.5% propylene by weight of the isotacticpropylene copolymer and/or having a melting point by DSC of greater than110° C.; and (c) blending the propylene polymer of step (a) with thecopolymer of step (b); and blending at step (c), or after, optionaladditives. The polypropylene of (b), the “second polypropylene,” may beprovided as having a desirably high MFR, such as greater than 500 g/10min, or can be provided as a polypropylene of relatively low MFR, whichin certain embodiments can be followed by the additional step ofperforming controlled rheology using a chain scissioning agent such asan organic peroxide, as is well known in the art.

To produce the elastic fibers and fabrics described herein, the one ormore RGPs are blended by any suitable means with at least one “secondpolypropylene.” In such a blend (or “composition”), the RGP is presentwithin the range of from 50 or 55 or 60 or 65 to 80 or 85 or 90 or 95 or99 wt %, by weight of the composition in one embodiment, and by weightof the fabric in another embodiment. The fabric/composition may alsoinclude other additives such as slip agents, oils, plasticizers,antioxidants and other additives that are known in the art as long as a35 g/m² basis weight fabric comprising the one or more RGPs maintains aCD Elongation value (as described herein) of greater than 50%.

Second Polypropylene (“SPP”)

The “second polypropylene” component is a crystalline polypropylenepolymer component that may be homopolypropylene, a copolymer comprisingpropylene, or some mixture thereof. The second polypropylene comprisesfrom 1 or 5 or 10 or 20 to 35 or 45 or 50 wt % of the fabric. In certainembodiments, the second polypropylene has one or more of the followingcharacteristics (A)-(D):

-   -   (A) The second polypropylene is predominately crystalline and        has a melting point of greater than 110° C., preferably greater        than 115° C., and most preferably greater than 130° C. The        second polypropylene may also have a heat of fusion greater than        25 J/g or 30 J/g or 40 J/g or 50 J/g 60 J/g or 70 J/g or 80 J/g        in certain embodiments as determined by DSC analysis, and within        the range of from 25 or 30 or 40 J/g to 70 or 80 or 90 or 100 or        120 or 150 or 160 J/g in other embodiments as determined by DSC.    -   (B) The polypropylene can vary widely in composition. For        example, substantially isotactic polypropylene homopolymers or        propylene copolymers containing equal to or less than 10 weight        percent of other monomer, i.e., at least 90% by weight propylene        derived units can be used. Further, the polypropylene can be        present in the form of a graft or block copolymer, in which the        blocks of polypropylene have substantially the same        stereoregularity as the propylene-α-olefin copolymer so long as        the graft or block copolymer has a sharp melting point above        110° C. and preferably above 115° C. and more preferably above        130° C., characteristic of the stereoregular propylene        sequences. The propylene polymer component may be a combination        of homopolypropylene, and/or random and/or block copolymers as        described herein. When the above propylene polymer component is        a random copolymer, the percentage of the copolymerized α-olefin        in the copolymer is up to 9% by weight, preferably 2%-8% by        weight, most preferably 2%-6% by weight. The preferred α-olefins        contain 2 or from 4 to 12 carbon atoms. The most preferred        α-olefin is ethylene. One, two or more α-olefins can be        copolymerized with propylene to form the SPP. Exemplary        α-olefins may be selected from the group consisting of ethylene;        1-butene; 1-pentene, 2-methyl-1-pentene, 3-methyl-1-butene;        1-hexene, 3-methyl-1-pentene, 4-methyl-1-pentene,        3,3-dimethyl-1-butene; 1-heptene; 1-hexene; 1-methylhexene;        dimethyl-1-pentene, trimethyl-1-butene; ethyl-1-pentene;        1-octene; methyl-1-pentene; dimethyl-1-hexene;        trimethyl-1-pentene; ethyl-1-hexene; methylethyl-1-pentene;        diethyl-1-butene; propyl-1-pentane; 1-decene; methyl-1-nonene;        1-nonene; dimethyl-1-octene; trimethyl-1-heptene;        ethyl-1-octene; methyl-1-ethylbutene; diethyl-1-hexene;        1-dodecene and 1-hexadodecene.    -   (C) The molecular weight of the second polypropylene can be        within the range of from 10,000 or 50,000 or 80,000 to 500,000        or 800,000 or 1,000,000 or 2,000,000, with a polydispersity        index (PDI, or molecular weight distribution, Mw/Mn) within the        range of from 1.5 to 2.5 or 3.0 or 4.0 or 20 or 40.0.    -   (D) The MFR (2.16 kg, 230° C.) of the second polypropylene,        either as a reactor grade (same meaning as above for the RGP) or        a controlled-rheology polypropylene, is within the range of from        20 or 100 or 200 or 300 or 500 or 600 to 1000 or 1500 or 2000 or        3000 or 5000 or 7500 g/10 min.

There is no particular limitation on the method for preparing the secondpolypropylene. However, in general, the polymer is a propylenehomopolymer obtained by homopolymerization of propylene in a singlestage or multiple stage reactors. Copolymers may be obtained bycopolymerizing propylene and ethylene and/or an α-olefin having from 4to 20 carbon atoms, preferably ethylene, in a single stage or multiplestage reactor by any suitable means.

The second polypropylene can be either homopolymer or a copolymer withother α-olefins. The second polypropylene may also be comprised ofcommonly available isotactic polypropylene compositions referred to asimpact copolymer or reactor copolymer. However these variations in theidentity of the second polypropylene are acceptable only to the extentthat all of the components of the second polypropylene are substantiallysimilar in composition and the second polypropylene is within thelimitations of the crystallinity and melting point indicated above. Thissecond polypropylene may also contain additives such as flow improvers,nucleators and antioxidants which are normally added to isotacticpolypropylene to improve or retain its properties. All of thesepolymers, alone or in a blend, may be referred to as the “secondpolypropylene.”

Exemplary commercial products suitable for use as the secondpolypropylene include the family of Escorene™ and Achieve™ brandpolypropylenes (ExxonMobil Chemical Co.), and Metocene™ brandpolypropylenes (LyondellBasell). The Achieve polymers are produced usingmetallocene catalyst systems. In certain embodiments, the metallocenecatalyst system produces a narrow molecular weight distribution polymer.The molecular weight distribution (MWD) as measured by weight averagedmolecular weight (Mw)/number averaged molecular weight (Mn) is typicallyin the range of 1.5 to 2.5 or 3.0 or 4.0 or 5.0. However, a broader MWDpolymer may be produced in a process with multiple reactors. Differentmolecular weight polymers can be produced in each reactor to broaden theMWD. Achieve polymer such as Achieve 3854 polypropylene, a 24 g/10 minMFR homopolymer can be used as the second polypropylene. Alternatively,Achieve polymer such as Achieve 6936G1 polypropylene, a 1500 MFRhomopolymer can be used as the second polypropylene. Polypropylenehomopolymer, random copolymer and impact copolymer produced byZiegler-Natta catalyst system have a relatively broad MWD (within therange of from 3.0 to 6.0). The resin can be modified by a process calledcontrolled rheology to reduce the MWD to improve spinning performance.Example of such product is PP3155, a 36 g/10 min MFR homopolymer(ExxonMobil Chemical Co.).

Additives

As mentioned above, a variety of additives may be incorporated into theembodiments described above used to make the fibers and fabric forvarious purposes. Such additives include, for example, stabilizers,surfactants, antioxidants, fillers, colorants, nucleating agents,anti-block agents and slip additives. Primary and secondary antioxidantsinclude, for example, hindered phenols, hindered amines, and phosphates.Nucleating agents include, for example, sodium benzoate and talc, andhighly crystalline propylene polymers. Other additives such asdispersing agents, for example, Acrowax™ C, can also be included. Slipagents include, for example, oleamide and erucamide. Catalystdeactivators are also commonly used, for example, calcium stearate,hydrotalcite, and calcium oxide, and/or other acid neutralizers known inthe art. Additives such as these may be present in the fibers, fabricsand/or compositions within the range of from 0.1 or 0.5 to 2 or 3 or 5wt %, as long as the elasticity of the fabrics made therefrom maintainthe desired elasticity (CD Elongation).

Other additives include, for example, fire/flame retardants,plasticizers, vulcanizing or curative agents, vulcanizing or curativeaccelerators, cure retarders, processing aids, tackifying resins,process oils (synthetic and/or natural) and the like. The aforementionedadditives of may also include fillers and/or reinforcing materials,either added independently or incorporated into an additive. Examplesinclude carbon black, clay, talc, calcium carbonate, mica, silica,silicate, combinations thereof, and the like.

Of course, the particular additive can be selected as desired to impartor improve specific surface characteristics of the composition andthereby modify the properties of the fabric made therefrom. A variety ofactive agents or chemical compounds have heretofore been utilized toimpart or improve various surface properties including, but not limitedto, absorbency, wettability, anti-static properties, anti-microbialproperties, anti-fungal properties, liquid repellency (e.g. alcohol orwater) and so forth. As an example, exemplary wetting agents that can bemelt-processed in order to impart improved wettability to the fiberinclude, but are not limited to, ethoxylated silicone surfactants,ethoxylated hydrocarbon surfactants, ethoxylated fluorocarbonsurfactants and so forth.

Formation of Polymer Composition and the Fabrics Therefrom

The blends (“compositions”) of the second polypropylene and RGP, andother optional additives may be prepared by any procedure that resultsin an intimate mixture of the components. For example, the componentscan be combined by melt pressing the components together on a Carverpress to a thickness of 0.5 millimeter (20 mils) and a temperature ofabout 180° C., rolling lip the resulting slab, folding the ends togetherand repeating the pressing, rolling, and folding operation 10 times.Internal mixers are particularly useful for solution or melt blending.Blending at a temperature of 180° C. to 240° C. in a BrabenderPlastograph for 1 to 20 minutes has been found satisfactory. Stillanother method that may be used for admixing the components involvesblending the polymers in a Banbury internal mixer above the fluxtemperature of all of the components, for example, 180° C. for 5minutes. A complete mixture of the polymeric components is indicated bythe uniformity of the morphology of the dispersion of secondpolypropylene and RGP. Continuous mixing may also be used. Theseprocesses are well known in the art and include single and twin screwmixing extruders, static mixers for mixing molten polymer streams of lowviscosity, impingement mixers, as well as other machines and processes,designed to disperse the RGP and the second polypropylene in intimatecontact. A particularly desirable mode of admixture would be the meltmixing of molten pellets of RGP and the second polypropylene in thedesired weight ratio within the confines of the extruder feeding thespinnerets for the formation of melt blown fibers.

In certain embodiments, the composition consists essentially of the RGPand second polypropylene; and in further embodiments, the fibers andfabrics produced from the compositions consist essentially of the RGPand second polypropylene.

The formation of nonwoven fabrics from polyolefins and their blendsgenerally requires the manufacture of fibers by extrusion followed byweaving or bonding. The extrusion process is typically accompanied bymechanical or aerodynamic drawing of the fibers. The elastic fabricsdescribed herein may be manufactured by any technique known in the art.Such methods and equipment are well known.

Meltblown fibers are fibers formed by extruding a molten thermoplasticmaterial through a plurality of fine, usually circular, die capillariesas molten threads or filaments into converging, usually hot and highvelocity, gas streams (e.g., air or nitrogen) to attenuate the filamentsof molten thermoplastic material and form fibers. During the meltblowingprocess, the diameter of the molten filaments is reduced by the drawingair to a desired size. Thereafter, the meltblown fibers are carried bythe high velocity gas stream and are deposited on a collecting surfaceto form at least one web of randomly disbursed meltblown fibers.Meltblown fibers may be continuous or discontinuous and are generallysmaller than 10 microns in average diameter.

In a conventional meltblowing process, molten polymer is provided to adie that is disposed between a pair of air plates that form a primaryair nozzle. Standard meltblown equipment includes a die tip with asingle row of capillaries along a knife edge. Exemplary die tips haveapproximately 30 capillary exit holes per linear inch of die width. Thedie tip is typically a 60° wedge-shaped block converging at the knifeedge at the point where the capillaries are located. The air plates inmany known meltblowing nozzles are mounted in a recessed configurationsuch that the tip of the die is set back from the primary air nozzle.However, air plates in some nozzles are mounted in a flush configurationwhere the air plate ends are in the same horizontal plane as the dietip; in other nozzles the die tip is in a protruding or “stick-out”configuration so that the tip of the die extends past the ends of theair plates. Moreover, more than one air flow stream can be provided foruse in the nozzle.

In some known configurations of meltblowing nozzles, hot air is providedthrough the primary air nozzle formed on each side of the die tip. Thehot air heats the die and thus prevents the die from freezing as themolten polymer exits and cools. In this way the die is prevented frombecoming clogged with solidifying polymer. The hot air also draws, orattenuates, the melt into fibers. Other schemes for preventing freezingof the die, such as that detailed in U.S. Pat. No. 5,196,207, usingheated gas to maintain polymer temperature in the reservoir, is alsoknown. Secondary, or quenching, air at temperatures above ambient isknown to be provided through the die head. Primary hot air flow ratestypically range from about 20 to 24 standard cubic feet per minute perinch of die width (SCFM/inch).

In certain embodiments the primary air pressure in the meltblown processtypically ranges from 2 or 5 to 8 or 10 or 15 pounds per square inchgauge (psig) at a point in the die head just prior to exit. Primary airtemperature typically ranges from 200 or 230 to 300 or 320 or 350° C. incertain embodiments, but temperatures of 400° C. are not uncommon. Theparticular temperature of the primary hot air flow will depend on theparticular polymer being drawn as well as other characteristics desiredin the meltblown web. The melt temperature of the compositions used tomake the fabrics described herein are at least that to form a melt ofthe composition and below the decomposition temperature of thecomponents of the blend, and in certain embodiments is within the rangeof from 200 or 220° C. to 280 or 300° C. Expressed in terms of theamount of composition flowing per inch of the die per unit of time,throughputs for the manufacture of fabrics using the compositionsdescribed herein are typically within the range of from 0.1 or 0.2 or0.3 to 1 or 1.25 grams per hole per minute (ghm). Thus, for a die having30 holes per inch, polymer throughput is typically about 2 to 5 or 7 or8 lbs/inch/hour (PIH). In certain embodiments, the composition ismeltblown at a melt temperature within the range of from 220 or 240 to280 or 300° C. and a throughput within the range of from 0.1 or 0.2 to1.25 or 2.0 g/hole/min.

Because such high temperatures must be used, a substantial amount ofheat is typically removed from the fibers in order to quench, orsolidify, the fibers leaving the die orifice. Cold gases, such as air,have been used to accelerate cooling and solidification of the meltblownfibers. In particular, secondary air flowing in a cross-flowperpendicular, or 90°, direction relative to the direction of fiberelongation, may be used to quench meltblown fibers and produce smallerdiameter fibers. In addition, a cooler pressurized quench air may beused and can result in faster cooling and solidification of the fibers.A cold air flow may be used to attenuate the fibers when it is desiredto decrease the attenuation of the fibers. Through the control of airand die tip temperatures, air pressure, and polymer feed rate, thediameter of the fiber formed during the meltblown process may beregulated. In certain embodiments, meltblown fibers produced herein havea diameter within the range of 0.5 or 1.0 or 2 to 3 or 4 or 5 microns.

After cooling, in certain embodiments the fibers are collected to form anonwoven web. In particular, the fibers are collected on a forming webthat comprises a moving mesh screen or belt located below the die tip.In order to provide enough space beneath the die tip for fiber forming,attenuation and cooling, forming distances of at least about 8 to 12inches between the polymer die tip and the top of the mesh screen arerequired in the typical meltblowing process. However, forming distancesas low as 4 inches are possible. The shorter forming distances may beachieved with attenuating air flows of at least 30° C. cooler than thetemperature of the molten polymer. In certain embodiments, the fabric isformed directly upon another fabric, a spunbond fabric in a particularembodiment.

In certain embodiments, the mechanical properties of the fabricsdescribed herein can be enhanced by the annealing the polymer fiber orother post fabrication processing. Annealing is often combined withmechanical orientation, in either or both the transverse direction (CD)or the machine direction (MD). It is preferred to employ an annealingstep in the process with or without mechanical orientation. Annealingmay also be done after fabrication of a non-woven material from thefibers. In certain embodiments, the fiber or fabric is annealed at atemperature within the range of from 50 or 60 to 130 or 160° C. Thermalannealing of the polymer blend is conducted by maintaining thecomposition or fabric at a temperature within the range above for aperiod of from 1 second to 1 minute, preferably between 1 and 10seconds. The annealing time and temperature can be adjusted for anyparticular blend composition comprising a second polypropylene and oneor two RGP by experimentation. Mechanical orientation can be done by thetemporary, forced extension of the polymer fiber for a short period oftime before it is allowed to relax in the absence of the extensionalforces. In another embodiment, the elastic fabrics described herein areannealed in a single-step by a heated roll (godet) during calendaringunder low tension. In other embodiments, the elastic nonwoven fabricsdescribed herein require little to no post fabrication processing.

It has been surprisingly found that the composition of the RGP, secondpolypropylene and other optional additives can be easily meltblown intofibers by extrusion through a spinneret followed by drawing, to thedesired denier. Additionally it has been found that the ability to spinfibers of these blends, as measured by the rate of spinning, isunaffected across a wide composition range. The relative amounts of theRGP in the composition as well as its particular properties are tailoredto meet the desired end characteristics of the fabric. The generaltrends shown in Table 1 demonstrate the versatility of the compositionsherein.

The fabrics described herein possess a number of desirable attributesthat can be tailored by adjusting the identity of either or both the RGPand second polypropylene as well as the amount of one or both. Thefabrics described herein are characterized by having a Handle value ofless than 60%, as measured in the fabric of 35 g/m² basis weight. Thebasis weight of the fabrics described herein is not limited and can bewithin the range of from, for example, 5 to 200 g/m² basis weight. Theuse of the specific “35 g/m² basis weight” is in reference to the basisweight of the fabric that is measured for, for example, its CDElongation value. Thus, the fabrics (measuring the fabric of 35 g/m²basis weight) may be further described by any combination of otherfeatures such as:

-   -   In certain embodiments, the fabric has an MD Elongation value        within the range of from 30 or 40 to 70 or 80%.    -   In certain embodiments, the fabric has a CD Elongation value        within the range of from 50 or 60 to 80 or 90%, and from greater        than 50 or 60% in other embodiments.    -   In certain embodiments, the fabric has a Hydrostatic Head value        of greater than 30 or 40 mbar, or within the range of from 20 or        30 to 90 or 100 mbar.    -   In certain embodiments, the fabric has an Air Permeabilty value        of greater than 30 or 40 ft³/ft²/min, and within the range of        from 20 or 30 to 90 or 100 ft³/ft²/min.    -   In certain embodiments, the fabric has a Handle value within the        range of from 10 or 15 to 40 or 50 or 60 g, or less than 60 or        50 or 40 grams in another embodiment.

TABLE 1 Dependence of Fabric property on nonwoven process conditions andcomposition variables Process/Annealing conditions Result Compositionvariable Calendar Process Line Take up MD CD RGP wt % SPP wt % Temp.Temp. Speed Tension elasticity elasticity higher lower same same samesame high high lower higher same same same same low low same same highersame same same high high same same lower same same same low low samesame same higher same same weak weak same same same lower same same weakweak same same same same higher — low high same same same same lowersame high low same same same same same higher low high same same samesame same lower high lower

The fabrics described herein may comprise part of a structure such as amultilayer laminate. As used herein, “multilayer laminate” refers to alaminate that includes two or more layers of fabric, at least one ofwhich is the fabric described herein. In certain embodiments, thestructure is a multilayer laminate wherein some of the layers arespunbond and some are meltblown such as spunbond/meltblown/spunbond(“SMS”) laminates and spunbond/meltblown/meltblown/spunbond (“SMMS”)laminates. The fibers and fabrics described herein enjoy wideapplication spanning several industries. For example, elastic fabricsdescribed herein may be used in the manufacture of hygiene products.Examples include diapers (child and adult) and feminine hygieneproducts. The elastic fabrics described herein are also useful formedical products. Examples include medical fabric for gowns, linens,towels, bandages, instrument wraps, scrubs, masks, head wraps, anddrapes. Additionally, the elastic fabrics described herein are useful inthe manufacture of consumer products. Examples include seat covers,domestic linens, tablecloths, and car covers. It is also contemplatedthat the inventive elastic fabrics may make-up either a portion or acomponent of the articles described above, such as an inner or outerlayer of a fabric. Other particular uses of the fabrics described hereininclude bed pads, bags, packaging material, packages, swimwear, bodyfluid impermeable backsheets, body fluid impermeable layers, body fluidpermeable layers, body fluid permeable covers, absorbents, tissues,nonwoven composites, liners, cloth linings, scrubbing pads, face masks,respirators, air filters, liquid filter, vacuum bags, oil and chemicalspill sorbents, thermal insulation, first aid dressings, medical wraps,fiberfill, outerwear, bed quilt stuffing, furniture padding, scrubbingpads, wipe materials, hosiery, automotive seats, upholstered furniture,carpets, carpet backing, filter media, disposable wipes, diapercoverstock, gardening fabric, geomembranes, geotextiles, sacks,housewrap, vapor barriers, breathable clothing, envelops, tamper evidentfabrics, protective packaging, and coasters.

EXAMPLES Procedure for the Preparation of the Reactor Grade RGP (“RGP”)

All polymerizations were performed in a liquid filled, single-stagecontinuous reactor using a metallocene catalyst system. The reactor wasa 0.5-liter stainless steel autoclave reactor and was equipped with astirrer, water cooling/steam heating element with a temperaturecontroller, and a pressure controller. Solvents, propylene, andcomonomers (ethylene) were first purified by passing through athree-column purification system. The purification system consisted ofan Oxiclear™ column (Model # RGP-R1-500 from Labclear) followed by a 5Aand a 3A molecular sieve columns. Purification columns were regeneratedperiodically whenever there was evidence of lower activity ofpolymerization. Both the 3A and 5A molecular sieve columns wereregenerated in-house under nitrogen at a set temperature of 260° C. and315° C., respectively. The molecular sieve material was purchased fromAldrich. The purified solvents and monomers were then chilled to about−15° C. by passing through a chiller before being fed into the reactorthrough a manifold. Solvent and monomers were mixed in the manifold andfed into reactor through a single tube. All liquid flow rates weremeasured using Brooksfield mass flow meters or Micro-MotionCoriolis-type flow meters.

The catalyst used to form the RGP used in the inventive examples wasrac-dimethylsilylbisindenyl hafnium dimethyl (obtained from Albemarle)pre-activated with N,N-dimethylanilinium tetrakis(pentafluorophenyl)(obtained from Albemarle) at a molar ratio of about 1:1 in toluene. Thecatalyst solution was kept in an inert atmosphere with less than 1.5 ppmwater content and was fed into reactor by a metering pump through aseparated line. Catalyst and monomer contacts took place in the reactor.

As an impurity scavenger, 250 ml of tri-n-octyl aluminum (TNOA) (25 wt %in hexane, Sigma Aldrich) was diluted in 22.83 kilogram of hexane. TheTNOA solution was stored in a 37.9-liter cylinder under nitrogenblanket. The solution was used for all polymerization runs until about90% of consumption, then a new batch was prepared. Pumping rates of theTNOA solution varied from polymerization reaction to reaction, rangingfrom 0 (no scavenger) to 4 ml per minute.

The reactor was first cleaned by continuously pumping solvent (e.g.,hexane) and scavenger through the reactor system for at least one hourat a maximum allowed temperature (about 150° C.). After cleaning, thereactor was heated/cooled to a temperature within the range of from 98to 110° C., the exact temperature depending upon the desired molecularweight of polymer product, using a water/steam mixture flowing throughthe reactor jacket and controlled at a set pressure with controlledsolvent flow. Monomers and catalyst solutions were then fed into thereactor when a steady state of operation was reached. An automatictemperature control system was used to control and maintain the reactorat a set temperature. Onset of polymerization activity was determined byobservations of a viscous product and lower temperature of water-steammixture. Once the activity was established and the system reachedequilibrium, the reactor was lined out by continuing operating thesystem under the established condition for a time period of at leastfive times of mean residence time prior to sample collection. Theresulting mixture, containing mostly solvent, polymer and unreactedmonomers, was collected in a collection box after the system reached asteady state operation. The collected samples were first air-dried in ahood to evaporate most of the solvent, and then dried in a vacuum ovenat a temperature of about 90° C. for about 12 hours. The vacuum ovendried samples were weighed to obtain yields. All the reactions werecarried out at a pressure of about 2.41 MPa-g.

Materials:

Comparative Materials

-   -   Propylene-α-olefin copolymer (F.1.1): A Vistamaxx™ elastomer        VM2320 with a MFR at 230° C. of 200 g/10 min (ExxonMobil        Chemical Co.).    -   Propylene-α-olefin copolymer (F.1.2): A Vistamaxx elastomer        VM2320 (ExxonMobil Chemical Co.) treated with 4500 ppm of a        peroxide, Luperox 101 (Arkema Chemical), with a MFR at 230° C.        of 1500 g/10 min.    -   Propylene-α-olefin copolymer (F.1.3): Escorene™ PP 3746G, a        homoisotactic polypropylene with a MFR at 230° C. of 1475 g/10        min (ExxonMobil Chemical Co.).    -   Propylene-α-olefin copolymer (F.1.4): Achieve 6936G1, a        homoisotactic polypropylene, made with a metallocene catalyst        with a MFR at 230° C. of 1600 g/10 min (ExxonMobil Chemical        Co.).        Inventive Materials

The inventive reactor grade RGP materials were prepared according to thepreviously mentioned polymerization procedure. Sample characteristicsare summarized in Table 2.

TABLE 2 Inventive Sample Characteristics Viscosity @ MFR @ wt % 190 C.230 C. Sample C2 Tm (C.) Tc (C.) ΔHf (J/g) (cp) (g/10 min) F.2.1 11.562.4 11.06 25 11010 1713 F.2.2 11.6 62.14  8.56 18.8 7091 2370 F.2.313.2 47.25 — 10 17920 — F.2.4 15.6 48.45 — 5 18420 —

-   -   Second polypropylene (SPP. 1): Escorene™ PP 3746G, a        homoisotactic polypropylene with a MFR at 230° C. of 1400 g/10        min (ExxonMobil Chemical Co.).    -   Second polypropylene (SPP.2): Achieve™ 6936G1 a homoisotactic        polypropylene, made with a metallocene catalyst with a MFR at        230° C. of 1600 g/10 min (ExxonMobil Chemical Co.).    -   Second polypropylene (SPP.3): an experimental Ziegler-Natta        produced isotactic homopolypropylene with a MFR at 230° C. of        800 g/10 min (after treating with peroxide), and melting point        (T_(m)) of about 160° C.

Example 1 Comparative Examples of Melt Blown Fabric

The fabrics were produced on a 500 mm wide melt blown line manufacturedby Reifenhäuser GmbH & Co. The sample composition, fabric properties,and processing conditions were as noted in below in Table 3.

Polymer pellets were introduced into the extruder of the melt blownprocess. After the polymer had been melted and homogenized in theextruder due to the shear and external heat, the extruder delivered thehomogenized molten polymer to a melt pump, which delivered the moltenpolymer to the melt blown die. The die consisted of a “coat hanger” todistribute the melt from the entrance to the die body to the whole widthof the die. The molten polymer had filtered and flowed to the die tip,which is basically a single row of capillaries (melt blown die tip). Thecapillary of each hole was 0.4 mm in diameter. The molten polymerexiting the die was attenuated by the high velocity air which is heatedto near the same temperature as the molten polymer at the die. The airwas supplied by a compressor, heated and introduced to the die body.Those who are skilled in the art are familiar with the general set up ofthe melt blown process. The air gap where the hot air exit was set at0.8 mm and the set-back of the die tip was also set at 0.8 mm. Thisallowed the air to exit at high velocity and attenuation of the fiber.The fiber exiting the die tip was attenuated first by the hot air andthen quenched by the ambient air. The melt blown fiber was thencollected on the moving porous belt (forming belt) to form the nonwovenmelt blown web. The web had sufficient strength that no thermal bondingwas required. The web was then tested for the physical properties.

Example 2 Comparative Examples of Melt Blown Fabric

The fabrics were produced on a 500 mm wide melt blown line manufacturedby Reifenhäuser GmbH & Co according to the procedure described inExample 1. Pellets of the comparative reactor grade RGP were blendedwith a peroxide in a white oil mixture, then introduced into theextruder for melt homogenization and molecular weight degradation viaperoxide initiated chain scission. The sample composition, fabricproperties, and processing conditions were as noted in below in Table 4.

Example 3 and Example 4 Comparative Examples of Melt Blown Fabric

Granules of the following polymers as in the Tables 5-7 were convertedinto melt blown fabric using the procedure outlined in Example 1. Thecomposition data, fabric properties and processing conditions are notedbelow in Table 5-7.

Example 5-Example 7 Inventive Examples of Melt Blown Fabric

A dry blend of reactor grade RGP and second polypropylene and anyadditional additives may be dry blended and fed directly into theextruder of the melt blown process. The dry blended pellets, granulesand additives were introduced into the extruder of the melt blownprocess. A slip concentrate included in some compositions is a 70/30Vistamaxx™ 2125/erucamide masterbatch. The erucamide is Polyvel™ S 1428,and Vistamaxx 2125 propylene-α-olefin is available from ExxonMobilChemical Company. Dry blended compositions as outlined in Table 8-Table13 were made into melt blown fabric by the procedure outlined earlier.The fabric properties and processing conditions are noted below in Table8-Table 13.

Test Methods

Differential Scanning Calorimetry

Differential Scanning Calorimetry (DSC) is described as follows: 6 to 10mg of a sheet of the polymer pressed at approximately 200° C. to 230° C.is removed with a punch die or part of a polymer pellet. The sample isplaced in a Differential Scanning Calorimeter (Perkin Elmer 7 SeriesThermal Analysis System) and cooled to −50° C. to −70° C. The sample isheated at 10° C./min to attain a final temperature of 200° C. to 220° C.The thermal output during this heating is recorded. The melting peak ofthe sample is typically peaked at 30° C. to 175° C. and occurs betweenthe temperatures of 0° C. and 200° C. The area under the thermal outputcurve, measured in Joules, is a measure of the heat of fusion (ΔH_(f) orH_(f)). The melting point (T_(m)) is recorded as the temperature of thegreatest heat absorption within the range of melting of the sample.

Tensile and Elongation of the Fabric

As used herein, the tensile strength and elongation of a fabric may bemeasured according to the ASTM test D-5035 with four modifications: 1)the jaw width is 5 in instead of 3 in, 2) test speed is 5 in/min insteadof 12 in/min, 3) metallic arc-type upper line grip and a flat lowerrubber grip instead of a flat metallic upper and a flat metallic ofother lower grip, and 6 MD and 6 CD measurements instead of 5 MD and 8CD measurements are made for each specimen. This test measures thestrength in pounds and elongation in percent of a fabric.

Extensibility is a desirable attribute for many applications. As statedabove, the tensile strength and elongation of a fabric may be measuredaccording to the ASTM D-5035 with four modifications: 1) the jaw widthis 5 in instead of 3 in, 2) test speed is 5 in/min instead of 12 in/min,3) metallic arc-type upper line grip and a flat lower rubber gripinstead of a flat metallic upper and a flat metallic of other lowergrip, and 6 MD and 6 CD measurements instead of 5 MD and 8 CDmeasurements are made for each specimen. It can be measured as “peakelongation” or “break elongation.” Peak elongation is percent increasein length of the specimen when the stress of the specimen is at itsmaximum. Break elongation is percent increase in length of the specimenwhen the specimen breaks. The elongation can be measured in the machinedirection (MD) of the fabric or the cross direction (CD) of the fabric.The MD elongation is normally lower than the CD due to machine directionorientation of the fibers. The Elongation values used throughout have anerror of ±10% of the reported percentage value. Thus, for example, areported value of 70% elongation has an expected value between 63% and77%.

Melt Flow Rate

The melt flow rate (MFR) is a measure of the viscosity of polymers. TheMFR is expressed as the weight of material which flows from a capillaryof known dimensions under a 2.16 kg load at 230° C. for a measuredperiod of time and is measured in grams/10 minutes according to ASTMtest 1238.

Softness of the Fabric (“Handle”)

The softness of a nonwoven fabric may be measured according to the“Handle-O-Meter” test as specified in operating manual on Handle-O-Metermodel number 211-5 from the Thwing-Albert Instrument Co. TheHandle-O-Meter reading is in units of grams. The modifications are: (1)Two specimens per sample were used and (2) Readings are kept below 100gram by adjusting the slot width used and the same slot width is usedthrough out the whole series of samples being compared. The Handlevalues used throughout have an error of ±25% of the reported percentagevalue.

Hydrostatic Pressure Test Procedure

“Hydrohead” is a measure of the liquid barrier properties of a fabric.The hydrohead test determines the height of water (in centimeters) whichthe fabric will support before a predetermined amount of liquid passesthrough. A fabric with a higher hydrohead reading indicates it has agreater barrier to liquid penetration than a fabric with a lowerhydrohead. The hydrohead test can be performed according to Federal TestStandard 191A, Method 5514, or with slight variations of this test asset forth below.

In this test, water pressure is measured to determine how much waterpressure is required to induce leakage in three separate areas of a testmaterial. The water pressure is reported in millibars (mbars) at thefirst sign of leakage in three separate areas of the test specimen. Thepressure in millibars can be converted to hydrostatic head height ininches of water by multiplying millibars by 0.402. Pressure measured interms of inches refers to pressure exerted by a number of inches ofwater. Hydrostatic pressure is pressure exerted by water at rest.

Apparatus used to carry out the procedure includes a hydrostatic headtester, such as TEXTEST FX-3000 available from ATI Advanced TestingInstruments Corp. of Spartenburg, S.C., a 25.7 cm² test head such aspart number FX3000-26 also available from ATI Advanced TestingInstruments Corp., purified water such as distilled, deionized, orpurified by reverse osmosis, a stopwatch accurate to 0.1 second, aone-inch circular level, and a cutting device, such as scissors, a papercutter, or a die-cutter.

Prior to carrying out this procedure, any calibration routinesrecommended by manufacturers of the apparatus being used should beperformed. Using the cutting device, the specimen is cut to theappropriate size. Each specimen has a minimum size that is sufficient toallow material to extend beyond the outer diameter of the test head. Forexample, the 25.7 cm² test head requires a 6-inch by 6-inch, or 6-inchdiameter specimen. Specimens should be free of unusual holes, tears,folds, wrinkles, or other distortions.

Prior to the test the hydrostatic head tester is level, and that thedrain faucet at the front of the instrument is closed. Pull the uppertest head clamp to the left side of the instrument. Pour approximately0.5 liter of purified water into the test head until the head is filledto the rim. Push the upper test head clamp back onto the dovetail andmake sure the plug is inserted into the socket at the left side of theinstrument. Turn the instrument on and allow the sensor to stabilize for15 minutes. Set the pressure gradient thumbwheel switch to 60 mbar/min.Make sure the drain faucet is closed. The water temperature should bemaintained at about 24° C. (±5° C.). Set the test head illumination forbest visibility of water droplets passing through the specimen.

Once the set-up is complete, slide the specimen onto the surface of thewater in the test head, from the front side of the tester. Make surethere are no air bubbles under the specimen and that the specimenextends beyond the outer diameter of the test head on all sides. If theupper test head clamp was removed for loading the specimen, push theclamp back onto the dovetail. Pull down the lever to clamp the specimento the test head and push the lever until it comes to a stop. Press the“Reset” button to reset the pressure sensor to “zero.” Press theStart/Pause button to start the test. Observe the specimen surface andwatch for water passing through the specimen. When water droplets formin three separate areas of the specimen, the test is complete. Any dropsthat form within approximately 0.13 inch (3.25 mm) of the edge of theclamp should be ignored. If numerous drops or a leak forms at the edgeof the clamp, repeat the test with another specimen. Once the test iscomplete, read the water pressure from the display and record. Press theReset button to release the pressure from the specimen for removal.Repeat procedure for desired number of specimen repeats.

Air Permeability

This test determines the airflow rate through a sample for a set areasize and pressure. The higher the airflow rate per a given area andpressure, the more open the fabric is, thus allowing more fluid to passthrough the fabric. Air permeability is determined using a pressure of125 Pa (0.5 inch water column) and is reported in cubic feet per minuteper square foot. The air permeability data reported can be obtainedusing a TEXTEST FX 3300 air permeability tester.

Fiber Diameter Test Procedures

Fiber diameters were tested using a Scanning Electron Microscope (SEM)Image Analysis of Meltblown Fiber Diameter test. The meltblown web wastested for Count-Based Mean Diameter and Volume-Based Mean Diameter.

Ethylene Content of RGP

The composition of the RGP was measured as ethylene weight percentaccording to the following technique. A thin homogeneous film of thesecond polypropylene, pressed at a temperature of or greater than 150°C. was mounted on a Perkin Elmer PE 1760 infra red spectrophotometer. Afull spectrum of the sample from 600 cm⁻¹ to 400 cm⁻¹ was recorded andthe ethylene weight percent of the second polypropylene was calculatedaccording to Equation 1 as follows: ethylene wt%=82.585−111.987X+30.045X²; wherein X is the ratio of the peak height at1155 cm⁻¹ and peak height at either 722 cm⁻¹ or 732 cm⁻¹, which ever ishigher.

Molecular Weight of the RGP: By GPC

Molecular weights (weight average molecular weight (Mw) and numberaverage molecular weight (Mn)) are determined using a Waters 150 SizeExclusion Chromatograph (SEC) equipped with a differential refractiveindex detector (DRI), an online low angle light scattering (LALLS)detector and a viscometer (VIS). The details of the detectorcalibrations have been described elsewhere (Reference: T. Sun, P. Brant,R. R. Chance, and W. W. Graessley, 34(19) MACROMOLECULES, 6812-6820(2001)); attached below are brief descriptions of the components.

The SEC with three Polymer Laboratories PLgel 10 mm Mixed-B columns, anominal flow rate 0.5 cm³/min, and a nominal injection volume 300 μL iscommon to both detector configurations. The various transfer lines,columns and differential refractometer (the DRI detector, used mainly todetermine eluting solution concentrations) are contained in an ovenmaintained at 135° C. The LALLS detector is the model 2040 dual-anglelight scattering photometer (Precision Detector Inc.). Its flow cell,located in the SEC oven, uses a 690 nm diode laser light source andcollects scattered light at two angles, 15° and 90°. Only the 15° outputwas used in these experiments. Its signal is sent to a data acquisitionboard (National Instruments) that accumulates readings at a rate of 16per second. The lowest four readings are averaged, and then aproportional signal is sent to the SEC-LALLS-VIS computer. The LALLSdetector is placed after the SEC columns, but before the viscometer.

The viscometer is a high temperature Model 150R (Viscotek Corporation).It consists of four capillaries arranged in a Wheatstone bridgeconfiguration with two pressure transducers. One transducer measures thetotal pressure drop across the detector, and the other, positionedbetween the two sides of the bridge, measures a differential pressure.The specific viscosity for the solution flowing through the viscometeris calculated from their outputs. The viscometer is inside the SEC oven,positioned after the LALLS detector but before the DRI detector.

Solvent for the SEC experiment was prepared by adding 6 grams ofbutylated hydroxy toluene (BHT) as an antioxidant to a 4 liter bottle of1,2,4-trichlorobenzene (TCB, Aldrich Reagent grade) and waiting for theBHT to solubilize. The TCB mixture was then filtered through a 0.7 μmglass pre-filter and subsequently through a 0.1 μm Teflon filter. Therewas an additional online 0.7 μm glass pre-filter/0.22 μm Teflon filterassembly between the high pressure pump and SEC columns. The TCB wasthen degassed with an online degasser (Phenomenex™ Model DG-4000) beforeentering the SEC.

Polymer solutions were prepared by placing dry polymer in a glasscontainer, adding the desired amount of TCB, then heating the mixture at160° C. with continuous agitation for about 2 hours. All quantities weremeasured gravimetrically. The TCB densities used to express the polymerconcentration in mass/volume units are 1.463 g/ml at room temperatureand 1.324 g/ml at 135° C. The injection concentration ranged from 1.0 to2.0 mg/ml, with lower concentrations being used for higher molecularweight samples.

Prior to running each sample the DRI detector and the injector werepurged. Flow rate in the apparatus was then increased to 0.5 ml/minute,and the DRI was allowed to stabilize for 8-9 hours before injecting thefirst sample. The argon ion laser was turned on 1 to 1.5 hours beforerunning samples by running the laser in idle mode for 20-30 minutes andthen switching to full power in light regulation mode. The error in theMw/Mn values discussed herein is typically ±15%.

TABLE 3 Example 1 1 2 3 4 5 6 7 Compositions F.1.1 (wt %) 100 100 100100 100 100 100 SPP.1 (wt %) — — — — — — — SPP.2 (wt %) — — — — — — —SPP.3 (wt %) — — — — — — — Properties MD Tensile Strength 0.4 0.6 0.71.3 1.5 0.9 0.3 (lb) MD Elongation (%) 89.8 96.2 141.3 230.3 161.8 158.0120.0 CD Tensile Strength 0.3 0.5 0.5 0.9 1.0 0.7 0.2 (lb) CD Elongation(%) 137.3 140.3 226.7 248.0 177.4 241.0 164.0 Handle (g) — — — — — 44.740.4 Hydrostatic head 44.8 22.9 35.3 42.3 28.0 32.9 8.8 (mbar) AirPermeability 69.1 82.0 57.8 31.9 36.6 56.8 187.9 (ft³/ft²/min)Conditions Melt Temperature (C.) 246 246 246 246 246 246 246 Throughput0.2 0.4 0.4 0.4 0.6 0.2 0.2 (g/hole/min) DCD (mm) 300 300 300 300 350300 300 Basis weight (g/m²) 35 55 70 100 135 35 70

TABLE 4 Example 2 Example 2- 1 2 3 4 5 Compositions F.1.2 (wt %) 90 9090 90 90 SPP.1 (wt %) 10 10 10 10 10 SPP.2 (wt %) — — — — — SPP.3 (wt %)— — — — — Properties MD Tensile Strength (lb) 0.6 0.6 0.9 0.5 0.8 MDElongation (%) 44.7 66.6 65.3 44.1 46.1 CD Tensile Strength (lb) 0.4 0.50.8 0.4 0.7 CD Elongation (%) 69.9 86.4 85.9 66.2 76.4 Handle (g) — — —— — Hydrostatic head (mbar) 17.6 28.5 30.5 18.8 28.6 Air Permeability(ft³/ft²/min) 45.4 65.7 43.3 127.2 45.8 Conditions Melt Temperature (C.)246 246 246 246 246 Throughput (g/hole/min) 299 299 299 299 299 DCD (mm)0.2 0.4 0.4 0.6 0.6 Basis weight (g/m²) 70 70 105 70 105

TABLE 5 Example 3 Example 3- 1 2 3 4 5 6 7 8 9 10 Compositions F.1.3 (wt%) 100 100 100 100 100 100 100 100 100 100 SPP.1 (wt %) — — — — — — — —— — SPP.2 (wt %) — — — — — — — — — — SPP.3 (wt %) — — — — — — — — — —Properties MD Tensile Strength 1.2 1.6 2.6 1.4 1.1 1.5 1.3 1.4 2.2 1.6(lb) MD Elongation (%) 1.3 1.0 0.8 1.3 0.8 0.5 1.8 1.1 0.8 14.5 CDTensile Strength 0.5 0.6 0.8 0.5 0.4 0.5 0.4 0.7 1.0 0.9 (lb) CDElongation (%) 2.3 1.5 1.0 1.9 1.3 0.7 2.5 2.0 1.0 20.5 Handle (g) 38.250.1 36.9 50.1 19.5 43.0 35.3 65.6 50.4 98.1 Hydrostatic head 34.4 35.433.3 25.4 20.1 17.4 47.6 37.0 28.1 61.3 (mbar) Air Permeability 44.531.4 14.7 44.7 35.7 15.0 57.0 34.5 21.1 58.6 (ft³/ft²/min) ConditionsMelt Temperature 266 266 266 266 266 266 266 266 266 249 (C.) Throughput0.4 0.4 0.4 0.6 0.6 0.6 0.8 0.8 0.8 0.4 (g/hole/min) DCD (mm) 200 200200 200 200 200 250 250 250 200 Basis weight (g/m²) 25 35 70 25 35 70 2535 70 25

TABLE 6 Example 3 Example 3- 11 12 13 14 15 16 17 18 19 CompositionsF.1.3 (wt %) 100 100 100 100 100 100 100 100 100 SPP.1 (wt %) — — — — —— — — — SPP.2 (wt %) — — — — — — — — — SPP.3 (wt %) — — — — — — — — —Properties MD Tensile Strength (lb) 2.1 4.0 1.6 2.3 4.5 1.4 1.9 3.7 2.1MD Elongation (%) 9.5 3.9 5.8 3.5 2.6 7.6 6.1 3.3 19.0 CD TensileStrength (lb) 1.4 2.4 0.9 1.1 2.2 0.8 1.2 2.3 1.6 CD Elongation (%) 20.411.4 10.0 5.5 3.7 17.0 12.5 5.5 25.0 Handle (g) 78.7 150.0 109.9 85.6144.0 95.6 74.9 149.0 65.5 Hydrostatic head (mbar) 74.8 88.0 62.3 68.589.6 57.0 63.0 76.4 72.1 Air Permeability 40.1 20.3 60.5 41.2 20.8 79.451.0 24.5 37.7 (ft³/ft²/min) Conditions Melt Temperature (C.) 249 249249 249 249 249 249 249 446 Throughput (g/hole/min) 0.4 0.4 0.6 0.6 0.60.8 0.8 0.8 0.2 DCD (mm) 200 200 200 200 200 250 250 250 200 Basisweight (g/m²) 35 70 25 35 70 25 35 70 35

TABLE 7 Example 4 Example 4- 1 2 3 4 Compositions F.1.4 (wt %) 100 100100 100 SPP.1 (wt %) — — — — SPP.2 (wt %) — — — — SPP.3 (wt %) — — — —Properties MD Tensile Strength (lb) 2.0 2.4 2.7 1.7 MD Elongation (%)17.8 23.1 16.9 23.9 CD Tensile Strength (lb) 1.7 1.9 1.5 1.6 CDElongation (%) 41.1 35.7 20.6 32.3 Handle (g) — — — — Hydrostatic head(mbar) 85.0 83.8 81.3 62.9 Air Permeability (ft³/ft²/min) 32.1 33.9 36.551.2 Conditions Melt Temperature (C.) 246 246 246 246 Throughput(g/hole/min) 0.2 0.4 0.6 0.6 DCD (mm) 200 200 200 300 Basis weight(g/m²) 35 35 35 35

TABLE 8 Example 5 Example 5- 1 2 3 4 5 6 7 8 9 10 11 12 13 14Compositions F.2.1 (wt %) 70 70 70 70 70 70 70 80 80 80 80 80 80 80SPP.1 (wt %) 30 30 30 30 30 30 30 20 20 20 20 20 20 20 SPP.2 (wt %) — —— — — — — — — — — — — — SPP.3 (wt %) — — — — — — — — — — — — — —Properties MD Tensile Strength (lb) 0.9 1.1 0.9 1.8 1.8 0.7 2.1 0.8 1.10.8 1.7 0.8 5.9 1.3 MD Elongation (%) 45.0 62.0 51.0 60.0 57.0 51.0 49.047.0 62.0 52.0 53.0 44.0 46.0 47.0 CD Tensile Strength (lb) 0.6 0.8 0.81.3 1.2 0.5 1.6 0.5 0.7 0.6 1.3 0.6 3.0 0.8 CD Elongation (%) 65.0 83.065.0 75.0 77.0 59.0 53.0 69.0 87.0 76.0 78.0 52.0 52.0 60.0 Handle (g)14.7 38.7 38.6 53.3 55.3 40.0 59.5 17.3 35.6 31.9 52.4 46.0 43.5 37.5Hydrostatic head (mbar) 62.0 54.3 44.8 65.0 63.9 30.9 69.1 30.0 67.851.4 62.8 36.6 34.9 54.9 Air Permeability (ft³/ft²/min) 49.8 52.4 65.425.4 24.8 79.2 22.5 95.3 54.1 66.8 27.2 60.1 12.8 27.4 Conditions MeltTemperature (C.) 230 230 230 230 230 230 230 230 230 230 230 230 230 230Throughput (g/hole/min) 0.2 0.2 0.4 0.4 0.4 0.4 0.6 0.2 0.2 0.4 0.4 0.40.4 0.6 DCD (mm) 200 300 350 350 300 200 300 200 300 350 350 200 200 300Basis weight (g/m²) 35 35 35 70 70 35 70 35 35 35 70 70 35 70

TABLE 9 Example 5 Example 5- 15 16 17 18 19 20 21 22 23 24 25 26 27 28Compositions F.2.1 (wt %) 80 80 80 80 80 80 80 80 80 80 80 80 85 85SPP.1 (wt %) — — — — — — — — — — — — — — SPP.2 (wt %) 20 20 20 20 20 20— — — — — — — — SPP.3 (wt %) — — — — — — 20 20 20 20 20 20 15 15Properties MD Tensile Strength 0.6 0.6 0.4 1.1 1.0 1.2 0.9 0.8 0.7 1.41.3 1.3 0.7 1.0 (lb) MD Elongation (%) 45.0 64.0 35.0 40.0 36.0 38.064.0 66.0 53.0 61.0 64.0 56.0 50.0 62.0 CD Tensile Strength 0.4 0.4 0.40.7 0.7 0.8 0.6 0.7 0.5 1.0 1.1 1.0 0.3 0.8 (lb) CD Elongation (%) 55.067.0 69.0 46.0 56.0 50.0 77.0 104.0 73.0 81.0 79.0 70.0 97.0 83.0 Handle(g) 13.3 26.2 31.8 47.0 42.5 54.7 15.4 38.0 36.8 50.1 58.2 41.8 10.466.9 Hydrostatic head 29.1 38.8 9.0 30.0 28.9 15.9 50.3 50.9 31.5 38.435.9 40.6 54.9 43.8 (mbar) Air Permeability 54.5 64.0 210.0 74.9 73.986.9 47.2 69.0 101.3 48.6 51.6 43.8 41.2 45.9 (ft³/ft²/min) ConditionsMelt Temperature (C.) 230 230 230 230 230 230 230 230 230 230 230 230230 230 Throughput 0.2 0.2 0.4 0.4 0.4 0.6 0.2 0.2 0.4 0.4 0.4 0.6 0.20.2 (g/hole/min) DCD (mm) 200 300 350 350 300 300 200 300 350 350 300300 300 300 Basis weight (g/m²) 35 35 35 70 70 70 35 35 35 70 70 70 3535

TABLE 10 Example 6 Example 6- 1 2 3 4 5 6 7 8 9 10 11 12 13 14Compositions F.2.2 (wt %) 70 70 70 70 70 70 70 80 80 80 80 80 80 80SPP.1 (wt %) 30 30 30 30 30 30 30 20 20 20 20 20 20 20 SPP.2 (wt %) — —— — — — — — — — — — — — SPP.3 (wt %) — — — — — — — — — — — — — —Properties MD Tensile Strength (lb) 0.9 1.1 0.9 1.8 1.8 0.7 2.1 0.8 1.10.8 1.7 0.8 5.9 1.3 MD Elongation (%) 45.0 62.0 51.0 60.0 57.0 51.0 49.047.0 62.0 52.0 53.0 44.0 46.0 47.0 CD Tensile Strength (lb) 0.6 0.8 0.81.3 1.2 0.5 1.6 0.5 0.7 0.6 1.3 0.6 3.0 0.8 CD Elongation (%) 65.0 83.065.0 75.0 77.0 59.0 53.0 69.0 87.0 76.0 78.0 52.0 52.0 60.0 Handle (g)14.7 38.7 38.6 53.3 55.3 40.0 59.5 17.3 35.6 31.9 52.4 46.0 43.5 37.5Hydrostatic head (mbar) 62.0 54.3 44.8 65.0 63.9 30.9 69.1 30.0 67.851.4 62.8 36.6 34.9 54.9 Air Permeability 49.8 52.4 65.4 25.4 24.8 79.222.5 95.3 54.1 66.8 27.2 60.1 12.8 27.4 (ft³/ft²/min) Conditions MeltTemperature (C.) 230 230 230 230 230 230 230 230 230 230 230 230 230 230Throughput (g/hole/min) 0.2 0.2 0.4 0.4 0.4 0.4 0.6 0.2 0.2 0.4 0.4 0.40.4 0.6 DCD (mm) 200 300 350 350 300 200 300 200 300 350 350 200 200 300Basis weight (g/m²) 35 35 35 70 70 35 70 35 35 35 70 70 35 70

TABLE 11 Example 6 Example 6- 15 16 17 18 19 20 21 22 23 24 25Compositions F.2.2 (wt %) 80 80 80 80 80 80 80 80 80 80 80 SPP.1 (wt %)20 20 20 20 20 20 20 20 20 20 20 SPP.2 (wt %) — — — — — — — — — — —SPP.3 (wt %) — — — — — — — — — — — Properties MD Tensile Strength (lb)0.9 1.0 0.8 1.4 0.7 0.8 1.7 1.3 0.7 0.5 0.6 MD Elongation (%) 49.0 53.053.0 55.0 29.0 37.0 49.0 56.0 38.0 42.0 37.3 CD Tensile Strength (lb)0.6 0.6 0.5 0.9 0.3 0.4 0.7 0.7 0.4 0.3 0.3 CD Elongation (%) 66.0 88.087.0 85.0 68.0 76.0 84.0 63.0 52.0 59.0 74.4 Handle (g) 19.6 35.0 29.035.5 10.0 30.6 39.8 35.7 17.0 11.3 12.3 Hydrostatic head (mbar) 47.177.4 57.1 79.6 84.5 69.8 98.0 55.0 52.9 52.8 42.9 Air Permeability(ft³/ft²/min) 51.5 34.9 45.5 18.6 28.4 38.8 15.3 30.3 67.3 89.2 61.1Conditions Melt Temperature (C.) 245 245 245 245 260 260 260 260 245 245245 Throughput (g/hole/min) 0.2 0.2 0.4 0.4 0.2 0.2 0.2 0.4 0.4 0.4 0.4DCD (mm) 200 300 350 350 250 300 300 350 350 300 300 Basis weight (g/m²)35 35 35 70 35 35 70 70 35 25 25

TABLE 12 Example 6 Example 6- 26 27 28 29 30 31 32 33 34 35 36 37 38 3940 Compositions F.2.2 (wt %) 80 80 80 80 80 80 80 79 79 79 79 79 79 7979 SPP.1 (wt %) 19 19 19 19 19 19 19 19 SPP.2 (wt %) 20 20 20 20 20 2020 — — — — — — — — SPP.3 (wt %) — — — — — — — — — — — — — — — Slipconcentrate — — — — — — — 2 2 2 2 2 2 2 2 (erucamide) Properties MDTensile Strength (lb) 0.6 0.6 0.4 1.1 1.0 0.7 1.4 0.7 0.5 0.6 1.4 1.41.2 1.3 0.6 MD Elongation (%) 19.0 39.0 27.0 53.0 47.0 28.0 37.0 39.167.2 56.1 38.5 55.2 53.5 38.4 46.7 CD Tensile Strength (lb) 0.3 0.3 0.20.6 0.6 0.4 0.8 0.4 0.4 0.3 0.8 0.9 0.8 0.9 0.3 CD Elongation (%) 34.060.0 45.0 47.0 42.0 67.0 52.0 57.4 83.5 42.1 48.4 68.3 54.9 51.3 51.3Handle (g) 14.7 13.5 14.7 34.7 39.5 12.4 41.5 10.3 8.6 9.3 35.7 34.032.6 41.3 11.2 Hydrostatic head (mbar) 71.1 77.5 24.4 56.6 38.4 81.867.4 55.1 52.3 26.0 32.4 43.0 39.0 19.5 20.9 Air Permeability 31.6 33.072.4 28.0 36.5 30.9 19.2 53.9 74.0 138.7 36.6 39.5 40.8 82.1 133.1(ft³/ft²/min) Conditions Melt Temperature (C.) 230 230 230 230 230 245245 249 249 249 249 249 249 249 249 Throughput (g/hole/min) 0.2 0.2 0.40.4 0.6 0.2 0.4 0.2 0.2 0.4 0.4 0.4 0.6 0.6 0.6 DCD (mm) 200 300 200 300300 300 300 200 300 200 200 300 300 200 200 Basis weight (g/m²) 35 35 3570 70 35 70 35 35 35 70 70 70 70 35

TABLE 13 Example 7 Example 7- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Compositions F.2.3 (wt %) 70 70 70 70 70 70 85 85 85 85 85 85 85 85 85SPP.1 (wt %) 30 30 30 30 30 30 15 15 15 15 15 15 15 15 15 SPP.2 (wt %) —— — — — — — — — — — — — — — SPP.3 (wt %) — — — — — — — — — — — — — — —Properties MD Tensile 0.8 0.7 1.0 2.0 1.2 0.5 1.32 1.26 0.58 1.33 1.571.21 0.96 0.32 0.92 Strength (lb) MD Elongation (%) 54.0 52.0 43.0 50.046.0 45.0 47 54 23 37 46 39 35 35 42 CD Tensile 0.5 0.5 0.6 1.3 0.8 0.30.78 0.87 0.38 0.69 0.93 0.62 0.64 0.16 0.65 Strength (lb) CD Elongation(%) 75.0 71.0 58.0 69.0 54.0 49.0 72 71 53 36 64 47 44 48 62 Handle (g)15.3 12.0 14.0 46.6 51.4 15.9 17.8 16.8 16.7 38.6 37.5 33.9 38.6 18.537.8 Hydrostatic head 68.9 82.9 78.5 76.5 34.9 26.1 88.9 73.5 69.1 82.485.1 67.5 35.1 36.4 38.9 (mbar) Air Permeability 39.6 37.3 34.6 18.826.4 100.2 32.02 42.91 33.74 13.22 19.11 22.03 23.98 44.6 42.92(ft³/ft²/min) Conditions Melt Temperature 230 230 230 230 230 230 230230 230 230 230 230 230 245 245 (C.) Throughput 0.2 0.2 0.4 0.6 0.6 0.60.2 0.2 0.4 0.4 0.4 0.6 0.6 0.2 0.4 (g/hole/min) DCD (mm) 200 300 200300 200 200 200 300 200 200 300 300 200 300 300 Basis weight (g/m²) 3535 35 70 70 35 35 35 35 70 70 70 70 35 70

Having described the elements of the fabrics in its various aspects andranges, described herein is, in a first embodiment:

-   1. A nonwoven fabric comprising (or consisting essentially of):    -   (a) within the range of from 50 to 99 wt %, by weight of the        fabric, of a reactor grade propylene-α-olefin copolymer        possessing;        -   (i) within the range of from 5 to 35 wt %, by weight of the            copolymer, of units derived from one or more of ethylene            and/or C₄ to C₁₂ α-olefins;        -   (ii) a melt flow rate (230° C./2.16 kg) within the range of            from 500 to 7500 g/10 min and a weight average molecular            weight of less than 200,000; and        -   (iii) a heat of fusion, ΔH_(f), within the range of from 0.5            to 75 J/g; and    -   (b) a second polypropylene having a melting point, T_(m), of        greater than 110° C. and a melt flow rate (230° C./2.16 kg)        within the range of from 20 to 7500 g/10 min;    -   wherein the fabric has a CD Elongation value of greater than 50%        (measuring the fabric of 35 g/m² basis weight).-   2. The nonwoven fabric of numbered embodiment 1, wherein the fabric    consists essentially of the reactor grade propylene-α-olefin    copolymer and second polypropylene.-   3. The nonwoven fabric of numbered embodiments 1 and 2, wherein a    weight average molecular weight of the reactor grade    propylene-α-olefin copolymer is within the range of from 10,000 to    200,000.-   4. The nonwoven fabric of any one of the previously numbered    embodiments, wherein the reactor grade propylene-α-olefin copolymer    has a melting point T_(m) of less than 100° C.-   5. The nonwoven fabric of any one of the previously numbered    embodiments, wherein chain scissioning byproducts are substantially    absent from the reactor grade propylene-α-olefin copolymer.-   6. The nonwoven fabric of any one of the previously numbered    embodiments, wherein the reactor grade propylene-α-olefin copolymer    is prepared by reacting propylene, ethylene and a metallocene    catalyst composition.-   7. The nonwoven fabric of any one of the previously numbered    embodiments, wherein the fabric has been annealed at a temperature    within the range of from 70 to 130° C. for 1 to 10 seconds.-   8. The nonwoven fabric of numbered embodiment 7, wherein the fabric    has an MD Elongation value within the range of from 30 to 80%, and a    CD Elongation value within the range of from 50 to 90% (measuring    the fabric of 35 g/m² basis weight in both cases).-   9. The nonwoven fabric of claim 7, wherein the fabric has a    Hydrostatic Head value of greater than 30 mbar (measuring the fabric    of 35 g/m² basis weight).-   10. The nonwoven fabric of numbered embodiment 7, wherein the fabric    has an Air Permeability value of greater than 40 ft³/ft²/min (12.2    m³/m²/min) (measuring the fabric of 35 g/m² basis weight).-   11. The nonwoven fabric of any one of the previously numbered    embodiments, wherein the fabric comprises from 70 to 90 wt %, by    weight of the composition, of the reactor grade propylene-α-olefin    copolymer.-   12. The nonwoven fabric of any one of the previously numbered    embodiments, wherein the reactor grade propylene-α-olefin copolymer    comprises within the range of from 8 to 18 wt %, by weight of the    copolymer, of ethylene-derived units.-   13. The nonwoven fabric of any one of the previously numbered    embodiments, wherein the second polypropylene is a propylene    homopolymer or propylene copolymer comprising from 0.01 to 5 wt %    comonomer, wherein the second polypropylene has a melting point of    110° C. or more.-   14. A structure comprising two or more layers of fabric comprising    at least one layer of the fabric of any one of the previously    numbered embodiments.-   15. A method of forming a nonwoven fabric of any one of the    previously numbered embodiments:    -   (a) reacting propylene with an α-olefin selected from ethylene        and C₄ to C₁₂ α-olefins and a bridged metallocene catalyst        composition at a temperature within the range of from 80 to 120°        C.;    -   (b) isolating a reactor grade propylene-α-olefin copolymer        possessing a melt flow rate within the range of from 500 to 7500        g/10 min and a weight average molecular weight of less than        200,000;    -   (c) blending within the range of from 50 to 99 wt %, by weight        of the fabric, of the reactor grade propylene-α-olefin copolymer        and a second polypropylene to form a composition; and    -   (d) meltblowing the composition to form a nonwoven fabric,        wherein the fabric has a CD Elongation value of greater than 50%        (measuring the fabric of 35 g/m² basis weight).-   16. The method of any one of the previously numbered embodiments,    further comprising the step of annealing the fibers or fabric at a    temperature within the range of from 70 to 130° C. for 1 to 10    seconds.

Also disclosed is the use of a nonwoven fabric comprising (a) within therange of from 50 to 99 wt %, by weight of the fabric, of a reactor gradepropylene-α-olefin copolymer possessing; (i) within the range of from 5to 35 wt %, by weight of the copolymer, of units derived from one ormore of ethylene and/or C₄ to C₁₂ α-olefins; (ii) a melt flow rate (230°C./2.16 kg) within the range of from 500 to 7500 g/10 min and a weightaverage molecular weight of less than 200,000; and (iii) a heat offusion, ΔH_(f), within the range of from 0.5 to 75 J/g; and (b) a secondpolypropylene having a melting point, T_(m), of greater than 110° C. anda melt flow rate (23° C./2.16 kg) within the range of from 20 to 7500g/10 min; wherein the fabric has a CD Elongation value of greater than50% (measuring the fabric of 35 g/m² basis weight).

What is claimed is:
 1. A meltblown nonwoven fabric comprising: (a)within the range of from 50 to 99 wt %, by weight of the fabric, of areactor grade propylene-α-olefin copolymer possessing; (i) within therange of from 5 to 35 wt %, by weight of the copolymer, of units derivedfrom ethylene; (ii) a melt flow rate (230° C./2.16 kg) within the rangeof from 1000 to 4000 g/10 min and a weight average molecular weight ofless than 200,000; and (iii) a heat of fusion, AH f, within the range offrom 0.5 to 75 J/g; and (iv) a crystallization temperature (Tc) withinthe range of from 0 to 40° C.; and (b) a second polypropylene having amelting point, T_(m), of greater than 110° C. and a melt flow rate (230°C./2.16 kg) within the range of from 20 to 7500 g/10 min, wherein thenon-woven fabric has a CD Elongation value within the range of from 50%to 90% (measuring the fabric of 35 g/m² basis weight) after beingannealed at a temperature within the range of from 70 to 130° C. for 1to 10 seconds.
 2. The nonwoven fabric of claim 1, wherein the fabricconsists essentially of the reactor grade propylene-α-olefin copolymerand second polypropylene.
 3. The nonwoven fabric of claim 1, wherein theweight average molecular weight of the reactor grade propylene-α-olefincopolymer is within the range of from 10,000 to 200,000.
 4. The nonwovenfabric of claim 1, wherein the reactor grade propylene-α-olefincopolymer has a melting point T_(m) of less than 100° C.
 5. The nonwovenfabric of claim 1, wherein chain scissioning byproducts aresubstantially absent from the reactor grade propylene-α-olefincopolymer.
 6. The nonwoven fabric of claim 1, wherein the reactor gradepropylene-α-olefin copolymer is prepared by reacting propylene, ethyleneand a metallocene catalyst composition.
 7. The nonwoven fabric of claim1, wherein the fabric has an MD Elongation value within the range offrom 30 to 80% (measuring the fabric of 35 g/m² basis weight).
 8. Thenonwoven fabric of claim 1, wherein the fabric has a Hydrostatic Headvalue of greater than 30 mbar (measuring the fabric of 35 g/m² basisweight).
 9. The nonwoven fabric of claim 1, wherein the fabric has anAir Permeability value of greater than 40 ft³/ft²/min (12.2 m³/m²/min)(measuring the fabric of 35 g/m² basis weight).
 10. The nonwoven fabricof claim 1, wherein the fabric comprises from 70 to 90 wt %, by weightof the composition, of the reactor grade propylene-α-olefin copolymer.11. The nonwoven fabric of claim 1, wherein the reactor gradepropylene-α-olefin copolymer comprises within the range of from 8 to 18wt %, by weight of the copolymer, of ethylene-derived units.
 12. Thenonwoven fabric of claim 1, wherein the second polypropylene is apropylene homopolymer or propylene copolymer comprising from 0.01 to 5wt % comonomer, wherein the second polypropylene has a melting point of110° C. or more.
 13. A structure comprising two or more layers of fabriccomprising at least one layer of the fabric of claim 1.